MANUPLAN is a tool for designing and analyzing manufacturing systems. In the early stages of manufacturing systems planning, it offers an efficient alternative to simulation modelling. MANUPLAN is based on a state-of-the-art analytical model. It is practical and easy to use, being simpler and quicker than simulations model. In a typical case, a system design that would have taken several weeks to evaluate using simulation was evaluated in under two days with MANUPLAN. Inputs to MANUPLAN are the basic system design data: information on part routing, equipment capacities and reliabilities, and production requirements. Outputs from MANUPLAN include part flow times, work-in-process levels, equipment utilizations, and production rates achieved. Each run by MANUPLAN takes only a few seconds. By changing the system design data, manufacturing designers can quickly understand the trade-offs between inventory levels, production requirements, flow times, and equipment reliabilities, for their system.